Probably, black hole (BH) is most intriguing as well as thermal objects [1]}
in the universe. The thermal object by virtue of it has both temperature and
entropy [2]}. This entropy is again proportional to the
area of the event (or outer) horizon (EH) and Cauchy (or inner) horizon (CH) i.e.
\({\cal S}_{\pm } = \frac{{\cal A}_{\pm }}{4}\) ,
where, \({\cal S}_{\pm }\)  is the Bekenstein-Hawking entropy (in units in which \(G=\hbar =c=k_{B}=1\) ) and
\({\cal A}_{\pm }\)  is area of both the horizons. Analogously, the temperature is proportional to the
surface gravity of EH (\({\cal H}^{+}\) ) and CH (\({\cal H}^{-}\) ) i.e.
\(T_{\pm } = \frac{\kappa _{\pm }}{2 \pi }\) ,
where \(T_{\pm }\)  is Hawking temperature evaluated on \({\cal H}^{\pm }\)  and
\(\kappa _{\pm }\)  is surface gravity of the BH evaluated on \({\cal H}^{\pm }\) .
